Abstract:

An alkali-developable black photosensitive resin composition for forming a
light-shielding barrier wall which comprises, as indispensable
components, (A) a carboxyl group-containing photosensitive prepolymer,
(B) a photopolymerization initiator, (C) a black pigment, and (D)
light-transmitting fine particles. By the use of this composition,
light-shielding barrier walls (11) having sufficient light-shielding
properties and a height of not less than 20 μm can be formed by
photolithography, without causing undercutting during development. In a
preferred embodiment, the black pigment (C) is a metal oxide, preferably
iron oxide, and the fine particles (D) are inorganic fine particles
having a refractive index of 1.40-1.90, preferably silica.

Claims:

1. An alkali-developable black photosensitive resin composition for
forming a light-shielding barrier wall having a height of not less than
20 μm by photolithography, which comprises (A) a carboxyl
group-containing photosensitive prepolymer, (B) a photopolymerization
initiator, (C) a black pigment, and (D) light-transmitting fine
particles.

2. The composition according to claim 1, wherein said black pigment (C) is
a metal oxide.

3. The composition according to claim 1, wherein said black pigment (C) is
iron oxide.

4. The composition according to claim 1, wherein said fine particle (D)
has a refractive index falling in the range of 1.40-1.90.

5. The composition according to claim 1, wherein said fine particle (D) is
silica.

6. A cured product obtained by curing said alkali-developable black
photosensitive resin composition set forth in claim 1 by either one or
both of irradiation of actinic energy rays and heating.

7. A light-shielding barrier wall formed from a cured product which is
obtained by curing said alkali-developable black photosensitive resin
composition set forth in claim 1 by either one or both of irradiation of
actinic energy rays and heating.

8. An optic having said light-shielding barrier wall set forth in claim 7.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This is a continuation of Application PCT/JP2007/060898, filed May
29, 2007, which was published under PCT Article 21(2).

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]This invention relates to an alkali-developable black photosensitive
resin composition for forming a light-shielding barrier wall having a
height of not less than 20 μm by photolithography, its cured product,
and a light-shielding barrier wall formed from the cured product
mentioned above. More particularly, the present invention relates to a
black photosensitive resin composition for forming black matrices of a
liquid crystal display device, an electronic display device, etc. and
light-shielding barrier walls etc. of optics which are used for image
transmission devices for writing optical systems of an optical printer
etc. or reading optical systems of a scanner, a copying machine, etc.

[0004]2. Description of the Prior Art

[0005]In recent years, in view of the demand for miniaturizing the
electronic equipment, the miniaturization of parts used for them is
indispensable. In addition thereto, high resolution is required for the
image transmission devices for writing optical systems, such as an
optical printer, and for reading optical systems, such as a scanner.
Heretofore, a gradient index rod lens array has been used for imaging
optical systems used in these image transmission devices. According to
this gradient index rod lens array, a very compact erect
equal-magnification imaging optical system can be realized. However,
since this lens array is produced by arranging many rod lens elements and
fixing them with a resin, it tends to generate unevenness of the
arrangement of rod-lens elements. Such uneven arrangement had affected
the resolution of the lens array and became the cause of generating
unevenness of picture in the high-resolution equipment.

[0006]As a lens array which can suppress occurrence of such uneven
arrangement, a resin erect lens array has been developed recently. A
resin erect lens array realizes an erect equal-magnification imaging
optical system by laminating two or more flat lens array plates having
many lenses formed in the surface of a transparent substrate. Although
such a resin erect lens array has been heretofore used in combination
with a liquid crystal display element to create a liquid crystal image in
a space or on an object. In order to apply a resin erect lens array to an
optical printer or a scanner, however, it is necessary to improve
resolution and an amount of transmitting light and to reduce the stray
light.

[0007]In order to reduce the unevenness of arrangement or the stray light
in these erect equal-magnification imaging optical systems, it is
desirable to form light-shielding portions in the recesses between lenses
so that the light collected with the lenses is efficiently transmitted.
As a method for forming light-shielding portions to be used in an erect
equal-magnification imaging optical system, a method of interposing a
sheet of light-shielding film between lens plates (see JP 2004-070268, A)
and a method of pouring black ink into the recess between lenses (see JP
2003-202411, A), for example, have so far been devised. However, both
methods have the problems in workability and the reproducibility of
openings.

[0008]On the other hand, in a color filter to be used for a display
material in a liquid crystal display, an electronic display, or the like,
a thin film of black matrix of several μm thickness is formed between
fine pixels colored at least two or more of hues for the purpose of
intercepting light and raising contrast and in order to prevent a
decrease in the intensity of color. This black matrix is generally formed
by photolithography which comprises the steps of applying a composition
containing a photosensitive prepolymer and a pigment, such as carbon
black, directly added thereto, onto a glass substrate, exposing the
resultant coating film to light according to a prescribed pattern, and
then performing development. Since the photolithography is suitable for
mass production owing to the good workability, it is widely used in the
printing industry or the electronics industry still now.

[0009]However, such a composition aiming at the light-shielding requires a
light-shielding black pigment, such as carbon black, to be contained in
the composition in a large amount to make the composition black.
Therefore, in photolithography it sustains remarkable underexposure and
tends to attain insufficient curing depth. As a result, there are such
problems that the undercutting will be easily produced in a developing
process and that the adhesiveness to a substrate will be inferior. That
is, it will be hardly possible to perform the patterning of a film having
the thickness of not less than 20 μm, particularly the thickness in
the range of 50 μm to 100 μm, by the photolithography with
sufficient degree of blackness because of insufficient curing property in
a deep portion of a coating film. Further, If an exposure dose is
increased in the step of exposure to light for the purpose of improving
the curing property in a deep portion, there is such a problem that
halation will become large and the resolution will decrease in proportion
to the increase of the exposure dose. Therefore, at present there is no
black photosensitive resin composition which is capable of coping with
the thick film and forming a film of sufficient degree of blackness
having the thickness of not less than 20 μm without causing the
undercutting during development.

SUMMARY OF THE INVENTION

[0010]The present invention has been made in view of the conventional
technology mentioned above. An object of the present invention is to
solve the above-mentioned problems involved in a photosensitive resin
composition for forming a light-shielding barrier wall and to provide an
alkali-developable black photosensitive resin composition which excels in
the curing property in a deep portion of a coating film and resolution in
the process of exposure to light and is capable of forming a cured
product exhibiting sufficient light-shielding effect without causing
undercutting during development even if the light-shielding barrier wall
has a height of not less than 20 μm, its cured product, and a
light-shielding barrier wall formed from this cured product.

[0011]To accomplish the object mentioned above, the present invention
provides an alkali-developable black photosensitive resin composition for
forming a light-shielding barrier wall having a height of not less than
20 μm by photolithography, characterized in that the composition
comprises, as indispensable components, (A) a carboxyl group-containing
photosensitive prepolymer, (B) a photopolymerization initiator, (C) a
black pigment, and (D) light-transmitting fine particles.

[0012]In a preferred embodiment, as the black pigment (C) mentioned above,
a metal oxide, preferably iron oxide is used, and as the fine particles
(D) mentioned above, fine particles having a refractive index falling in
the range of 1.40-1.90, preferably silica is used.

[0013]According to the present invention, there are further provided a
cured product obtained by curing the alkali-developable black
photosensitive resin composition mentioned above by irradiation of
actinic energy rays and/or by heating and a light-shielding barrier wall
formed from the cured product mentioned above.

[0014]Further, the present invention provides an optic having such a
light-shielding barrier wall. A light-shielding barrier wall of the
present invention is suitable for optics, such as a lens, a prism, a
color filter, and CCD. Although the light-shielding barrier wall is
applicable to any lenses, such as a single lens and a lens array, it is
particularly suitable for a plate-like microlens array.

[0015]Since the alkali-developable black photosensitive resin composition
of the present invention contains (D) light-transmitting fine particles
as an indispensable component besides (A) a carboxyl group-containing
photosensitive prepolymer, (B) a photopolymerization initiator, and (C) a
black pigment, even if a light-shielding barrier wall having a height of
not less than 20 μm is formed by photolithography, it excels in the
curing property in a deep portion of a coating film and resolution in the
process of exposure to light, and thus it is possible to form a thick
patterned film which exhibits sufficient light-shielding effect without
causing undercutting during development.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]Other objects, features, and advantages of the invention will become
apparent from the following description taken together with the drawings,
in which:

[0017]FIG. 1 is a schematic fragmentary sectional view for explaining the
process of forming light-shielding barrier walls in a resin erect lens
array by photolithography using the black photosensitive resin
composition of the present invention; and

[0018]FIG. 2 is a fragmentary sectional view schematically illustrating
the resin erect lens array having the light-shielding barrier walls
produced by the method shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019]The present inventors, after pursuing a diligent study in search of
a method for solving the problems mentioned above, have found that when
(D) light-transmitting fine particles are incorporated into a composition
containing as indispensable components (A) a carboxyl group-containing
photosensitive prepolymer, (B) a photopolymerization initiator which
generates radical species by irradiation of light, and (C) a black
pigment, though the degree of blackness becomes low accordingly, it is
possible to secure sufficient light-shielding effect by forming a thick
light-shielding barrier wall having a height of not less than 20 μm
and to attain sufficient curing-property in a deep portion of a coating
film in the process of exposure to light because the actinic energy rays
reach even the depths owing to the light transmittance of the fine
particles (D), and that the above-mentioned purpose can be thus
accomplished. The present invention has been perfected based on these
findings.

[0020]Now, the functions of the alkali developable black photosensitive
resin composition of the present invention will be described below with
reference to the accompanying drawings.

[0021]When a light-shielding barrier wall is formed in a resin erect lens
array by photolithography using the alkali-developable black
photosensitive resin composition of the present invention, first, a
coating film 4 of the black photosensitive resin composition is formed in
a flat lens array plate 1 having a plurality of lenses 2 formed on the
surface of a transparent substrate, as shown in FIG. 1. Subsequently, a
photomask 5 having a predetermined exposure pattern corresponding to a
barrier wall pattern is superposed on this coating film 4, and the
coating film is selectively irradiated with actinic energy rays for
exposure. Alternatively, laser beams etc. are scanned along the recesses
3 between the lenses 2 for direct imaging exposure. Then, after
separating the photomask 5 from the plate, unexposed areas are developed
with an aqueous alkaline solution to obtain a resin erect lens array 10
having the light-shielding barrier walls 11 formed along the recesses 3
between the lenses 2, as shown in FIG. 2. The light-shielding barrier
walls of a high aspect ratio having a desired height can be formed by
repeating each step of application, exposure, and development.
Incidentally, in this specification the "height" of the light-shielding
barrier wall refers to the height from the deepest position contacting
the substrate to the uppermost surface of the light-shielding barrier
wall. For example, in the case of the resin erect lens array 10 having
the light-shielding barrier walls 11 formed as shown in FIG. 2, it refers
to the height from the basal bottom of the recess 3 to the uppermost
surface of the light-shielding barrier wall 11.

[0022]According to the present inventors' researches, if the height of the
light-shielding barrier wall formed in this way is not less than 20
μm, it is possible to secure such sufficient light-shielding effect
that the transmittance of light is 5% or less, preferably 2% or less,
even if the degree of blackness is relatively low. Further, since the
aspect ratio can be enlarged, the light diffusion in a transparent part
can be effectively prevented by the three-dimensional control of light.
According to the light-shielding barrier wall of the present invention,
the aspect ratio of 5 or more can also be achieved. If the aspect ratio
of 5-10 is achieved, the light diffusion in a transparent part can be
effectively prevented by the three-dimensional control of light.
Moreover, since the black photosensitive resin composition of the present
invention contains the light-transmitting fine particles (D) and light is
transmitted via the light-transmitting fine particles during exposure to
light, the actinic energy rays reach even the depths and sufficient
curing property in a deep portion of a coating film is acquired.
Therefore, a coating film obtained excels in resolution and does not
cause the undercutting during development, and thus the barrier wall
which exhibits sufficient light-shielding effect can be formed. Since the
particles (D), particularly inorganic particles are added to the black
photosensitive resin composition of the present invention, the thermal
expansion coefficient of the resultant light-shielding barrier wall
becomes low and the hardness thereof becomes high. As a result, the
light-shielding barrier wall excels in thermal stability and does not
cause cracks etc., and the stability of the light-shielding barrier wall
against stress is also improved. Incidentally, the reflection of light at
a film surface can also be suppressed by making the surface of a
light-shielding barrier wall into the satin-like state.

[0023]In this specification, the "transmittance of light" refers to that
measured by the use of an ultraviolet-visible spectrophotometer while
irradiating a 20-μm thick dry film with light having a wavelength of
400-800 nm in the thickness direction. The transmittance of light should
be measured with a fixed thickness for comparison, because the more the
thickness becomes large, the more the transmittance of light becomes low,
even with the same degree of blackness.

[0024]Now, the black photosensitive resin composition of the present
invention will be described in detail below.

[0025]First, as the carboxyl group-containing photosensitive prepolymers
(A) to be used in the present invention, the following unsaturated
group-containing polycarboxylic resins may be cited:

[0026](1) products obtained by the reaction of (a) a polyfunctional epoxy
compound having at least two epoxy groups in its molecule with (b) an
unsaturated monocarboxylic acid and the subsequent reaction of (c) a
saturated or unsaturated polybasic acid anhydride with the resultant
hydroxyl group,

[0027](2) products obtained by causing (a) a polyfunctional epoxy compound
having at least two epoxy groups in its molecule to react with (b) an
unsaturated monocarboxylic acid and (d-1) a compound having one reactive
group other than an alcoholic hydroxyl group capable of reacting with an
epoxy group in its molecule, preferably (d-2) a compound having at least
one alcoholic hydroxyl group and one reactive group other than the
alcoholic hydroxyl group capable of reacting with an epoxy group in its
molecule, and subsequently causing the resultant product with (c) a
saturated or unsaturated polybasic acid anhydride,

[0028](3) products obtained by causing (g) a compound having one epoxy
group and an ethylenically unsaturated double bond in its molecule to
react with part of carboxyl groups of a copolymer of (e) an unsaturated
carboxylic acid and (f) a compound having an ethylenically unsaturated
double bond,

[0029](4) products obtained by causing (g) a compound having one epoxy
group and an ethylenically unsaturated double bond in its molecule to
react with a copolymer of (e) an unsaturated carboxylic acid and (f) a
compound having an ethylenically unsaturated double bond and subsequently
causing (c) a saturated or unsaturated polybasic acid anhydride to react
with the resultant hydroxyl group,

[0030](5) products obtained by causing (i) a hydroxyalkyl (meth)acrylate
to react with a copolymer of (h) an unsaturated dibasic acid anhydride,
such as maleic anhydride, and (f) a compound having an ethylenically
unsaturated double bond.

[0031]Incidentally, the term "(meth)acrylate" as used in the present
specification refers collectively to acrylate and methacrylate, and this
holds good for other similar expressions.

[0032]The acid value of such a photosensitive prepolymer (A), though
having an appropriate range thereof varied with the kind of prepolymer,
should generally fall in the range of 50 to 150 mg KOH/g, preferably in
the range of 60 to 120 mg KOH/g. Any deviation of the acid value from the
aforementioned range is undesirable because the resin will manifest
insufficient solubility in an aqueous alkaline solution if the acid value
is less than 50 mg KOH/g. Conversely, the acid value exceeding 150 mg
KOH/g will give cause to deteriorate the various properties of the cured
film such as resistance to alkalis, resistance to water, and resistance
to moisture.

[0033]The photosensitive prepolymer (A) of above-mentioned (1) is a
carboxyl group-containing photosensitive resin obtained by the reaction
of (a) a polyfunctional epoxy compound having at least two epoxy groups
in its molecule, preferably a solid polyfunctional epoxy compound, with
(b) a photosensitive unsaturated monocarboxylic acid and the subsequent
reaction of (c) a saturated or unsaturated polybasic acid anhydride with
the resultant hydroxyl group.

[0035]In the case of the above-mentioned copolymer of glycidyl
(meth)acrylate and a compound containing an ethylenically unsaturated
double bond, the molar fraction of glycidyl (meth)acrylate is desired to
be in the range of 20-60 mol %. If the molar fraction of glycidyl
(meth)acrylate to the copolymer is less than 20 mol %, the copolymer will
be at a disadvantage in acquiring an unduly low photocuring property due
to the reduction in the amount of addition of the unsaturated
monocarboxylic acid. Conversely, if the molar fraction of glycidyl
(meth)acrylate exceeds 60 mol %, the copolymer will be at a disadvantage
in failing to allow the synthesis to proceed smoothly. Further, in the
case of such a copolymer of glycidyl (meth)acrylate and a compound
containing an ethylenically unsaturated double bond, the weight-average
molecular weight thereof is desired to be in the range of 10,000 to
70,000, preferably in the range of 15,000 to 60,000. If the
weight-average molecular weight is less than 10,000, the resultant
coating film will be at a disadvantage in acquiring unduly low dryness to
the touch of finger. Conversely, if it exceeds 70,000, the composition
will be at a disadvantage in acquiring an unduly low developing property.

[0036]As concrete examples of the unsaturated monocarboxylic acid (b)
mentioned above, acrylic acid, methacrylic acid, itaconic acid,
β-carboxylethyl acrylate, β-carboxylethyl methacrylate, and the
compounds obtained by the addition of a polybasic acid anhydride to a
hydroxyl group-containing (meth)acrylate may be cited. Among other
unsaturated monocarboxylic acids cited above, acrylic acid and
methacrylic acid prove to be particularly desirable from the viewpoint of
the photosensitivity of the photosensitive prepolymer obtained and the
storage stability of the composition. These unsaturated monocarboxylic
acids (b) may be used either singly or in the form of a mixture of two or
more members.

[0037]The ratio of addition of the unsaturated monocarboxylic acid to the
polyfunctional epoxy compound (a) mentioned above is preferred to be 0.95
to 1.10 equivalent weights per one equivalent weight of an epoxy group of
the polyfunctional epoxy compound. If the amount of addition of the
unsaturated monocarboxylic acid is less than 0.95 equivalent weight, it
is at a disadvantage that unreacted epoxy groups remain and the storage
stability of the resultant prepolymer after addition of the saturated or
unsaturated polybasic acid anhydride will be deteriorated. Conversely, if
the amount exceeds 1.10 equivalent weights, it is at a disadvantage that
the unreacted unsaturated monocarboxylic acid remains and an offensive
smell will be increased.

[0038]As concrete examples of the saturated or unsaturated polybasic acid
anhydride (c) mentioned above, alicyclic dibasic acid anhydrides such as
methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride,
hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, nadic
anhydride, 3,6-endomethylenetetrahydrophthalic anhydride,
methylendomethylenetetrahydrophthalic anhydride, and tetrabromophthalic
anhydride; aliphatic or aromatic polybasic acid anhydrides such as
succinic anhydride, maleic anhydride, itaconic anhydride, octenylsuccinic
anhydride, pentadodecenylsuccinic anhydride, phthalic anhydride, and
trimellitic anhydride may be cited. These saturated or unsaturated
polybasic acid anhydrides may be used either singly or in the form of a
combination of two or more members. Among other polybasic acid anhydrides
cited above, alicyclic dibasic acid anhydrides prove to be particularly
desirable from the viewpoint of developability.

[0039]The amount of addition of the saturated or unsaturated polybasic
acid anhydride (c) is desired to be in such a proportion that the
anhydride group is in the range of 0.3 to 0.8 equivalent weight per one
equivalent weight of an alcoholic hydroxyl group caused by the reaction
of the polyfunctional epoxy compound (a) with the unsaturated
monocarboxylic acid (b) mentioned above, preferably such that the acid
value of the produced photosensitive prepolymer (A) falls in the range of
50 to 150 mg KOH/g.

[0040]The photosensitive prepolymer (A) of above-mentioned (2) is a
carboxyl group-containing photosensitive resin obtained by the reaction
of (a) a polyfunctional epoxy compound having at least two epoxy groups
in its molecule, preferably a solid polyfunctional epoxy compound, with
(b) an unsaturated monocarboxylic acid which is photosensitive and (d-1)
a compound having one reactive group (for example, carboxyl group,
phenolic hydroxyl group, secondary amino group, etc.) other than an
alcoholic hydroxyl group capable of reacting with an epoxy group in its
molecule, preferably (d-2) a compound having at least one alcoholic
hydroxyl group and one reactive group other than an alcoholic hydroxyl
group capable of reacting with an epoxy group in its molecule, and the
subsequent reaction of (c) a saturated or unsaturated polybasic acid
anhydride with the resultant product.

[0041]By the reaction of the aforementioned compound (d-1) having one
reactive group other than an alcoholic hydroxyl group capable of reacting
with an epoxy group in its molecule to the polyfunctional epoxy compound,
though the density of photosensitive groups decreases in comparison with
the carboxyl group-containing photosensitive resin (1) mentioned above,
the hydrophobic nature of the resultant resin may be increased depending
on the selection of the compound and thus the resistance to gold plating
and PCT resistance may be improved. As the compound (d-1) having the
hydrophobic nature and having one reactive group other than an alcoholic
hydroxyl group capable of reacting with an epoxy group in its molecule,
alkyl phenols such as pentyl phenol, dipentyl phenol, octyl phenol, nonyl
phenol, and dodecyl phenol; and monocarboxylic acids such as n-hexanoic
acid, dimethyl butyrate, ethyl butyrate, benzoic acid, toluic acid, and
ethyl benzoate may be cited.

[0042]Furthermore, by the reaction of the compound (d-2) having at least
one, alcoholic hydroxyl group, preferably primary alcoholic hydroxyl
group, and one reactive group other than an alcoholic hydroxyl group
capable of reacting with an epoxy group in its molecule to the
polyfunctional epoxy compound, though the density of photosensitive
groups decreases in comparison with the carboxyl group-containing
photosensitive resin (1) mentioned above, the carboxyl group is
introduced into the site apart from the main skeleton when the saturated
or unsaturated polybasic acid anhydride (c) is caused to react with the
resultant product. As a result, the resultant photosensitive prepolymer
has the flexibility and can be developed even if it has a low acid value.

[0043]As the compound (d-2) having at least one alcoholic hydroxyl group,
preferably primary alcoholic hydroxyl group, and one reactive group other
than an alcoholic hydroxyl group capable of reacting with an epoxy group
in its molecule, for example, polyhydroxy monocarboxylic acids such as
dimethylol propionic acid, dimethylol acetic acid, dimethylol butyric
acid, dimethylol valeric acid, and dimethylol caproic acid; hydroxyalkyl
phenols or hydroxyalkyl cresols such as bis(hydroxymethyl)phenol,
hydroxymethyl-di-t-buthyl phenol, p-hydroxyphenyl-2-methanol,
p-hydroxyphenyl-3-propanol, p-hydroxyphenyl-4-butanol, hydroxyethyl
cresol, 2,6-dimethyl-4-hydroxymethyl phenol,
2,4-dihydroxymethyl-2-cyclohexyl phenol, trimethylol phenol, and
3,5-dimethyl-2,4,6-trihydroxymethyl phenol; esterification products of a
phenol having a carboxyl group-containing substituent such as
hydroxybenzoic acid, hydroxyphenylbenzoic acid and hydroxyphenoxybenzoic
acid with ethylene glycol, propylene glycol, glycerol, diethylene glycol,
etc.; monoethylene oxide adduct of bisphenol, monopropylene oxide adduct
of bisphenol; p-hydroxyphenetyl alcohol; and dialkanol amines such as
diethanol amine and diisopropanol amine may be cited. As the particularly
preferred compounds, dimethylol propionic acid and p-hydroxyphenetyl
alcohol, for example, may be cited.

[0044]The synthesis of the carboxyl group-containing photosensitive resin
(2) mentioned above is attained by the first method which comprises
causing an unsaturated monocarboxylic acid (b) [or a compound (d-1, d-2)]
to react with a polyfunctional epoxy compound (a), then causing a
compound (d-1, d-2) [or an unsaturated monocarboxylic acid (b)] to react
with the resultant reaction product, or by the second method which
comprises causing simultaneous reaction of the polyfunctional epoxy
compound (a), the unsaturated monocarboxylic acid (b), and the compound
(d-1, d-2). Though these two methods are both available, the second
method proves more advantageous. Appropriately, the reaction mentioned
above is accomplished between one equivalent weight of the epoxy group of
the polyfunctional epoxy compound (a) and a total of about 0.8-1.3 mols,
particularly preferably about 0.9-1.1 mols, of the unsaturated
monocarboxylic acid (b) and the compound (d-1, d-2) mentioned above.
Properly, the ratio of the amounts of the unsaturated monocarboxylic acid
(b) and the compound (d-1, d-2) to be used is such that the amount of the
compound (d-1, d-2) to be used may fall in the range of 0.05 to 0.5 mol,
preferably 0.1 to 0.3 mol, based on 1 mol of the total of the amounts of
the unsaturated monocarboxylic acid (b) and the compound (d-1, d-2).

[0045]The photosensitive prepolymer (A) of above-mentioned (3) is a
carboxyl group-containing photosensitive resin obtained by causing (g) a
photosensitive compound having one epoxy group and an ethylenically
unsaturated double bond in its molecule to react with part of carboxyl
groups (the carboxyl group required for the alkali-development should be
remained) of a copolymer of (e) an unsaturated carboxylic acid and (f) a
compound having an ethylenically unsaturated double bond. The
weight-average molecular weight of the copolymer of (e) the unsaturated
carboxylic acid and (f) the compound having an ethylenically unsaturated
double bond, which is a skeleton of this carboxyl group-containing
photosensitive resin (3), is desired to be in the range of 10,000 to
70,000, preferably in the range of 15,000 to 60,000. If the
weight-average molecular weight is less than 10,000, the resultant
coating film will be at a disadvantage in acquiring unduly low dryness to
the touch of finger. Conversely, if it exceeds 70,000, the composition
will be at a disadvantage in acquiring an unduly low developing property.

[0046]As the unsaturated carboxylic acid (e) mentioned above, unsaturated
monocarboxylic acids, such as acrylic acid, methacrylic acid, half esters
of a hydroxyl group-containing (meth)acrylate and a saturated dibasic
acid anhydride, and half esters of maleic anhydride and alcohols;
unsaturated dicarboxylic acids, such as maleic acid, fumaric acid, and
itaconic acid, etc. may be cited. These unsaturated carboxylic acids may
be used either singly or in the form of a combination of two or more
members.

[0047]As the compound (f) having an ethylenically unsaturated double bond
mentioned above, for example, styrene, chlorostyrene, and
α-methylstyrene; acrylates, methacrylates or fumarates possessing
substituent(s) such as methyl, ethyl, propyl, isopropyl, n-butyl,
isobutyl, t-butyl, amyl, 2-ethylhexyl, octyl, capryl, nonyl, dodecyl,
hexadecyl, octadecyl, cyclohexyl, isobornyl, methoxyethyl, butoxyethyl,
2-hydroxyethyl, 2-hydroxypropyl, or 3-chloro-2-hydroxypropyl;
monoacrylates or monomethacrylates of polyethylene glycol and
monoacrylates or monomethacrylates of polypropylene glycol; vinyl
acetate, vinyl butyrate, and vinyl benzoate; maleimides such as
cyclohexylmaleimide and phenylmaleimide; olefins such as ethylene and
propylene; and acrylonitrile may be cited. These compounds may be used
either singly or in the form of a combination of two or more members.

[0048]As the compound (g) having one epoxy group and an ethylenically
unsaturated double bond in its molecule mentioned above, glycidyl
(meth)acrylate, β-methylglycidyl (meth)acrylate,
β-ethylglycidyl (meth)acrylate,
N-[4-(2,3-epoxypropoxy)-3,5-dimethylbenzyl]acrylamide,
N-[4-(2,3-epoxypropoxy)-3,5-dimethylbenzyl]methacrylamide, glycidyl
crotonate, 3,4-epoxycyclohexylmethyl (meth)acrylate, etc. may be cited.
Among other compounds cited above, glycidyl (meth)acrylate proves to be
desirable from the viewpoint of reactivity.

[0049]The photosensitive prepolymer (A) of above-mentioned (4) is a
carboxyl group-containing photosensitive resin obtained by causing an
epoxy group of (g) a compound having one epoxy group and an ethylenically
unsaturated double bond in its molecule to react with a carboxylic group
of a copolymer of (e) an unsaturated carboxylic acid and (f) a compound
having an ethylenically unsaturated double bond and subsequently causing
(c) a saturated or unsaturated polybasic acid anhydride to react with the
resultant hydroxyl group. Since this carboxyl group-containing
photosensitive resin (4) has the carboxyl group separated from the main
skeleton as compared with the carboxyl group-containing photosensitive
resin (3) mentioned above, it exhibits high reactivity and improved
developing property. The weight-average molecular weight of the copolymer
of (e) the unsaturated carboxylic acid and (f) the compound having an
ethylenically unsaturated double bond, which is a skeleton of this
carboxyl group-containing photosensitive resin (4), is desired to be in
the range of 10,000 to 70,000, preferably in the range of 15,000 to
60,000, like the carboxyl group-containing photosensitive resin (3)
mentioned above. If the weight-average molecular weight is less than
10,000, the resultant coating film will be at a disadvantage in acquiring
unduly low dryness to the touch of finger. Conversely, if it exceeds
70,000, the composition will be at a disadvantage in acquiring an unduly
low developing property.

[0050]The photosensitive prepolymer (A) of above-mentioned (5) is a
carboxyl group-containing photosensitive resin obtained by causing (i) a
hydroxyalkyl (meth)acrylate to react with a copolymer of (h) an
unsaturated dibasic acid anhydride, such as maleic anhydride, and (f) a
compound having an ethylenically unsaturated double bond. The
weight-average molecular weight of the copolymer of (h) the unsaturated
dibasic acid anhydride and (f) the compound having an ethylenically
unsaturated double bond, which is a skeleton of this carboxyl
group-containing photosensitive resin (5), is desired to be in the range
of 1,000 to 20,000, preferably in the range of 2,000 to 10,000. If the
weight-average molecular weight is less than 1,000, the resultant coating
film will be at a disadvantage in acquiring unduly low dryness to the
touch of finger. Conversely, if it exceeds 20,000, the synthesis of the
copolymer will be allowed only with difficulty and the composition will
be at a disadvantage in acquiring an unduly low developing property.

[0052]As the hydroxyalkyl (meth)acrylate (i) mentioned above,
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
4-hydroxybutyl (meth)acrylate, etc. may be cited. It is preferred that
such a compound should be added in a proportion of not less than the
number of equivalent of the acid anhydride group of the unsaturated
dibasic acid anhydride (h) mentioned above to make it react with the acid
anhydride group. The reason is because the storage stability of the
composition will become poor if the residual acid anhydride group is
present therein.

[0053]Among other photosensitive prepolymers (A) mentioned above, in the
black photosensitive resin composition of the present invention
exhibiting high shielding ability, the photosensitive prepolymers of
above-mentioned (3), (4) and (5) containing fewer functional groups which
exhibit absorption in the wavelength region sensitive to ultraviolet
light, such as an aromatic ring, are preferred, and the photosensitive
prepolymer of above-mentioned (4) which excels in the photosensitivity
and the developing property is particularly preferred.

[0054]The photopolymerization initiator of the component (B) which
constitutes the black photosensitive resin composition of the present
invention is a radical generator which generates an active radical by
irradiation of light. Any known and widely used compounds such as, for
example, aminoacetophenones like
2-methylthio-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one and
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one; and
thioxanthones like 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone,
and 2-chlorothioxanthone may be used. These photo-radical polymerization
initiators may be used either singly or in the form of a combination of
two or more members. The amount of the aforementioned photo-radical
polymerization initiator to be incorporated in the composition is desired
to be in the range of 0.1 to 30 parts by weight, based on 100 parts by
weight of the aforementioned photosensitive prepolymer (A). If the amount
of the photo-radical polymerization initiator to be used is less than the
lower limit of the range mentioned above, the composition will not be
photo-cured by irradiation of actinic energy rays or the irradiation time
should be prolonged, and a coating film of satisfactory properties will
be obtained only with difficulty. Conversely, even if the photo-radical
polymerization initiator is added to the composition in a large amount
exceeding the upper limit of the range mentioned above, the composition
will not attain the further improvement in the curing property and such a
large amount is not desirable from the economical viewpoint.

[0055]The black pigment of the component (C) which constitutes the black
photosensitive resin composition of the present invention is not limited
to a particular one insofar as it has sufficient light-shielding effect.
As the examples thereof, a metal oxide, carbon black, lamp black, bone
black, graphite, aniline black, cyanine black, titanium black, etc. may
be cited. As a metal oxide, those containing one or more oxides of Fe,
Cr, Mn, Co, etc. as main components thereof, for example, CrO3,
Cr2O3, MnO, Mn3O4, Mn2O3, MnO2, FeO,
Fe2O3, Fe3O4, CoO, CO3O4, NiO, Cu2O,
ZrO2, MoO3, TiO2, etc. may be cited. Further, composite
metal oxides, such as Mn2O3--CuO--Fe2O3,
CoO--Cr2O3--Fe2O3,
CuO--Mn2O3--Cr2O3, and CuO--Cr2O3, may also
be used. Among other metal oxides cited above, iron oxide is preferred
from the viewpoint of printing properties, embedding properties, and
defoaming properties. From the viewpoint of the degree of resolution, the
black pigment (C) is preferred to have an average particle diameter of
not more than 20 μm, preferably not more than 5 μm. The amount of
the black pigment (C) to be incorporated in the composition is desired to
be in the proportion of 0.1-7 vol. %, preferably 0.3-6 vol. %, of the
total volume of the composition. If the amount of the black pigment to be
used is less than 0.1 vol. %, the degree of blackness which shows
sufficient light-shielding effect will be obtained only with difficulty.
Conversely, the amount exceeding 7 vol. % is not preferred because the
composition will tend to cause the reduction in the hardness of the
resultant coating film.

[0056]The light-transmitting fine particles of the component (D) which
constitutes the black photosensitive resin composition of the present
invention is added for the purpose of improving such characteristics as
the curing property in a deep portion of a coating film, the adhesiveness
and hardness of a coating film. Both inorganic particles and organic
particulates may be used as long as they are light-transmitting fine
particles. As concrete examples of the inorganic fine particles,
well-known and widely used inorganic fillers such as barium sulfate,
talc, and silica may be cited. On the other hand, as the organic fine
particulates, for example, powdery cross-linked acrylic polymer (such as,
for example, MR-2G and MR-7G manufactured by Soken Chemical & Engineering
Co., Ltd., and TECHPOLYMER manufactured by Sekisui Plastics Co., Ltd.)
etc. may be cited. It is desirable that these fine particles (D) should
exhibit small difference in refractive index between the particle and an
organic component, such as the photosensitive prepolymer (A), in the
composition so that they can serve as the optical path for curing a
coating film to a deep portion thereof while suppressing halation,
without hindering advance of the light within a coating film when
photo-cured. For example, those having a refractive index in the range of
1.40-1.90, preferably 1.45-1.65 are desirable. Among other particles,
silica is more preferred from the viewpoint of a refractive index. The
amount of the fine particles (D) to be incorporated in the composition is
desired to be not less than 50 parts by weight and not more than 500
parts by weight, preferably not less than 80 parts by weight and not more
than 200 parts by weight, based on 100 parts by weight of the
photosensitive prepolymer (A) mentioned above. If the amount thereof is
less than 50 parts by weight, the curing property in a deep portion of a
coating film and the adhesiveness of a coating film will be deteriorated.
Conversely, the amount exceeding 500 parts by weight is not preferred
because the composition will cause the reduction in the hardness of the
coating film. From the viewpoint of the degree of resolution, the fine
particles (D) are preferred to have an average particle diameter of not
more than 20 μm, preferably not more than 5 μm. Particularly, the
use of the fine particles in combination of coarse grain and fine grain
is preferred because a cured film will assume the lusterless state which
prevents irregular reflection of light, thereby improving the
light-shielding effect.

[0057]The black photosensitive resin composition of the present invention
may incorporate therein, as occasion demands, a photopolymerizable
monomer (E) for the purpose of improving photo-curing property or the
like. As the photopolymerizable monomer (E), any polyfunctional monomers
such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, ethylene glycol
di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, an adduct of bisphenol
A diglycidyl ether with 2 mols of (meth)acrylic acid, trimethylolpropane
tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tetra
(meth)acrylates may be suitably used, but the photopolymerizable monomer
is not limited to these compounds. The amount of a photopolymerizable
monomer (E) is desired to be used in the proportion of not more than 60
parts by weight, based on 100 parts by weight of the photosensitive
prepolymer (A). In case the amount exceeds 60 parts by weight, the
resultant coating film will be at a disadvantage in acquiring unduly low
dryness to the touch of finger.

[0058]The black photosensitive resin composition of the present invention
may incorporate therein, as occasion demands, an organic solvent (F) for
dilution for the purpose of adjusting the viscosity of the composition.
As the organic solvents (F), any well-known and widely used organic
solvents such as, for example, ketones like methylethyl ketone and
cyclohexanone; aromatic hydrocarbons like toluene, xylene, and
tetramethyl benzene; glycol ethers like cellosolve, methyl cellosolve,
butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene
glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene
glycol diethyl ether, and tripropylene glycol monomethyl ether; esters
like ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate,
butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate,
propylene glycol monomethylether acetate, dipropylene glycol monomethyl
ether acetate, and propylene carbonate; aliphatic hydrocarbons like
octane and decane; and petroleum solvents like petroleum ether, petroleum
naphtha, and solvent naphtha may be used. These organic solvents may be
used either singly or in the form of a combination of two or more
members.

[0059]The black photosensitive resin composition of the present invention
may incorporate therein, as desired, a well-known and widely used
additive such as a thermopolymerization inhibitor, a thickening agent, an
anti-foaming agent, a leveling agent, and a coupling agent.

[0060]The black photosensitive resin composition of the present invention
obtained as described above is adjusted to a level of viscosity suitable
for coating by addition of a diluent (the above-mentioned
photopolymerizable monomer as a reactive diluent or the above-mentioned
organic solvent), thereafter applied by a suitable coating method, such
as a screen printing method, a curtain coating method, a roll coating
method, a dip coating method, and a spin coating method, to a desired
substrate, and then predried at a temperature in the approximate range of
60 to 120° C., for example, thereby to evaporate the organic
solvent from the composition and give rise to a coating film. When the
composition is in the state of a dry film, it may be simply laminated on
the substrate. Thereafter, when the composition coated on the substrate
is irradiated with actinic energy rays or heated, it hardens promptly.

[0061]Since in the black photosensitive resin composition of the present
invention the photosensitive prepolymer (A) contains the carboxyl group,
a patterned film may be formed by selectively exposing the coating film
to actinic energy rays through a photomask having a prescribed exposure
pattern or by directly projecting a laser beam on the coating film
according to a prescribed image pattern and then developing the unexposed
area of the coating film with an aqueous alkaline solution. Further, a
patterned thick film of desired thickness may be formed by repeating each
process of application, exposure to light, and development.

[0062]As an aqueous alkaline solution to be used in the process of
development mentioned above, aqueous alkaline solutions of sodium
hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate,
sodium silicate, ammonia, organic amines, tetramethylammonium hydroxide,
etc. can be used. The concentration of an alkali in the developing
solution may be proper generally in the range of 0.1 to 5.0 wt. %. As the
developing method, various known methods such as dipping development,
paddling development, and spraying development may be adopted.

[0064]Now, the present invention will be described more specifically below
with reference to working examples and comparative examples. It should be
noted, however, that the following Examples are intended to be merely
illustrative of and in any sense restrictive of the present invention.
Wherever the term "parts" is used hereinbelow, it invariably refers to
that based on weight unless otherwise specified.

Examples 1, 2 and Comparative Examples 1-3

[0065]The black photosensitive resin compositions containing components
accounting for varying ratios of combination shown in Table 1 were
prepared, wherein the black strength of each composition was adjusted to
such a level that the transmittance of light of a wavelength of 400-800
nm through a dry film of 20 μm thickness measured using an
ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation)
should be 1%. Each composition was tested and evaluated for the following
characteristics.

<Characteristic Evaluation 1> Curing property in a deep portion of a
coating film:

[0066]Each of the black photosensitive resin compositions of Examples 1, 2
and Comparative Examples 1-3 prepared in varying ratios of combination
shown in Table 1 was applied onto a soda lime glass substrate to form a
dried coating film of 50 μm thickness. Each substrate was exposed to
light from the back side of the glass by the use of an
ultra-high-pressure mercury lamp with various exposure doses and then
developed with an aqueous 1 wt. % sodium carbonate solution for 120
seconds so as to cause over development. The curing property in a deep
portion of a coating film was evaluated by determining the thickness of
the remaining coating film. The results are shown in Table 2.

[0067]Each of the black photosensitive resin compositions of Examples 1, 2
and Comparative Examples 1-3 prepared in varying ratios of combination
shown in Table 1 was applied onto a soda lime glass substrate to form a
dried coating film of 20 μm thickness. Each substrate was exposed to
light by the use of an ultra-high-pressure mercury lamp through a
negative mask of a line/space pattern of L/S=80/400 μm and then
developed with an aqueous 1 wt. % sodium carbonate solution for 30
seconds. The line width of the obtained pattern was measured with a light
microscope. The results are shown in Table 3. Incidentally, the pattern
of which line width is hardly measured was evaluated on the following
criterion.

[0068]Δ: Breakage of pattern occurred due to undercutting.

[0069]X: Pattern was separated by the development and the coating film was
not remained.

[0070]Each of the black photosensitive resin compositions of Examples 1, 2
and Comparative Examples 1-3 prepared in varying ratios of combination
shown in Table 1 was applied onto a soda lime glass substrate to form a
dried coating film of 20 μm thickness. Each substrate was exposed to
light by the use of an ultra-high-pressure mercury lamp through a
negative mask of a line/space pattern of L/S=80/400 μm with various
exposure doses and then developed with an aqueous 1 wt. % sodium
carbonate solution for 30 seconds. Thereafter, the state of the cured
film after the tape peeling test was visually examined to evaluate the
adhesiveness to the substrate. The results are shown in Table 4. The
criterion for evaluation of adhesiveness is as follows. With respect to
the substrate in which peeling of a film has been fully confirmed with a
prescribed exposure dose, subsequent examination with an exposure dose
lower than that exposure dose was not done, which is indicated by "-" in
Table 4.

[0071]◯: Absolutely no peeling of the film from the substrate
observed.

[0073]While certain specific working examples have been disclosed herein,
the invention may be embodied in other specific forms without departing
from the spirit or essential characteristics thereof. The described
examples are therefore to be considered in all respects as illustrative
and not restrictive, the scope of the invention being indicated by the
appended claims rather than by the foregoing description and all changes
which come within the meaning and range of equivalency of the claims are,
therefore, intended to be embraced therein.

[0074]The black photosensitive resin composition of the present invention
is advantageously applicable for the formation of a light-shielding
barrier wall which is used in various fields, such as a black matrix of a
liquid crystal display device, an electronic display device, etc., and
image transmission devices for writing optical systems of an optical
printer etc. or reading optical systems of a scanner, a copying machine,
etc.

[0075]The International Application PCT/JP2007/060898, filed May 29, 2007,
describes the invention described hereinabove and claimed in the claims
appended hereinbelow, the disclosure of which is incorporated here by
reference.